/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.sdk.extensions.joinlibrary;



import com.bff.gaia.unified.sdk.coders.KvCoder;

import com.bff.gaia.unified.sdk.transforms.DoFn;

import com.bff.gaia.unified.sdk.transforms.PTransform;

import com.bff.gaia.unified.sdk.transforms.ParDo;

import com.bff.gaia.unified.sdk.transforms.join.CoGbkResult;

import com.bff.gaia.unified.sdk.transforms.join.CoGroupByKey;

import com.bff.gaia.unified.sdk.transforms.join.KeyedPCollectionTuple;

import com.bff.gaia.unified.sdk.values.KV;

import com.bff.gaia.unified.sdk.values.PCollection;

import com.bff.gaia.unified.sdk.values.TupleTag;



import static com.bff.gaia.unified.vendor.guava.com.google.common.base.Preconditions.checkNotNull;



/**

 * Utility class with different versions of joins. All methods join two collections of key/value

 * pairs (KV).

 */

public class Join {



  /**

   * PTransform representing an inner join of two collections of KV elements.

   *

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   */

  public static class InnerJoin<K, V1, V2>

      extends PTransform<PCollection<KV<K, V1>>, PCollection<KV<K, KV<V1, V2>>>> {



    private transient PCollection<KV<K, V2>> rightCollection;



    private InnerJoin(PCollection<KV<K, V2>> rightCollection) {

      this.rightCollection = rightCollection;

    }



    public static <K, V1, V2> InnerJoin<K, V1, V2> with(PCollection<KV<K, V2>> rightCollection) {

      return new InnerJoin<>(rightCollection);

    }



    @Override

    public PCollection<KV<K, KV<V1, V2>>> expand(PCollection<KV<K, V1>> leftCollection) {

      checkNotNull(leftCollection);

      checkNotNull(rightCollection);



      final TupleTag<V1> v1Tuple = new TupleTag<>();

      final TupleTag<V2> v2Tuple = new TupleTag<>();



      PCollection<KV<K, CoGbkResult>> coGbkResultCollection =

          KeyedPCollectionTuple.of(v1Tuple, leftCollection)

              .and(v2Tuple, rightCollection)

              .apply("CoGBK", CoGroupByKey.create());



      return coGbkResultCollection

          .apply(

              "Join",

              ParDo.of(

                  new DoFn<KV<K, CoGbkResult>, KV<K, KV<V1, V2>>>() {

                    @ProcessElement

                    public void processElement(ProcessContext c) {

                      KV<K, CoGbkResult> e = c.element();



                      Iterable<V1> leftValuesIterable = e.getValue().getAll(v1Tuple);

                      Iterable<V2> rightValuesIterable = e.getValue().getAll(v2Tuple);



                      for (V1 leftValue : leftValuesIterable) {

                        for (V2 rightValue : rightValuesIterable) {

                          c.output(KV.of(e.getKey(), KV.of(leftValue, rightValue)));

                        }

                      }

                    }

                  }))

          .setCoder(

              KvCoder.of(

                  ((KvCoder) leftCollection.getCoder()).getKeyCoder(),

                  KvCoder.of(

                      ((KvCoder) leftCollection.getCoder()).getValueCoder(),

                      ((KvCoder) rightCollection.getCoder()).getValueCoder())));

    }

  }



  /**

   * PTransform representing a left outer join of two collections of KV elements.

   *

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   */

  public static class LeftOuterJoin<K, V1, V2>

      extends PTransform<PCollection<KV<K, V1>>, PCollection<KV<K, KV<V1, V2>>>> {



    private transient PCollection<KV<K, V2>> rightCollection;

    private V2 nullValue;



    private LeftOuterJoin(PCollection<KV<K, V2>> rightCollection, V2 nullValue) {

      this.rightCollection = rightCollection;

      this.nullValue = nullValue;

    }



    public static <K, V1, V2> LeftOuterJoin<K, V1, V2> with(

        PCollection<KV<K, V2>> rightCollection, V2 nullValue) {

      return new LeftOuterJoin<>(rightCollection, nullValue);

    }



    @Override

    public PCollection<KV<K, KV<V1, V2>>> expand(PCollection<KV<K, V1>> leftCollection) {

      checkNotNull(leftCollection);

      checkNotNull(rightCollection);

      checkNotNull(nullValue);

      final TupleTag<V1> v1Tuple = new TupleTag<>();

      final TupleTag<V2> v2Tuple = new TupleTag<>();



      PCollection<KV<K, CoGbkResult>> coGbkResultCollection =

          KeyedPCollectionTuple.of(v1Tuple, leftCollection)

              .and(v2Tuple, rightCollection)

              .apply("CoGBK", CoGroupByKey.create());



      return coGbkResultCollection

          .apply(

              "Join",

              ParDo.of(

                  new DoFn<KV<K, CoGbkResult>, KV<K, KV<V1, V2>>>() {

                    @ProcessElement

                    public void processElement(ProcessContext c) {

                      KV<K, CoGbkResult> e = c.element();



                      Iterable<V1> leftValuesIterable = e.getValue().getAll(v1Tuple);

                      Iterable<V2> rightValuesIterable = e.getValue().getAll(v2Tuple);



                      for (V1 leftValue : leftValuesIterable) {

                        if (rightValuesIterable.iterator().hasNext()) {

                          for (V2 rightValue : rightValuesIterable) {

                            c.output(KV.of(e.getKey(), KV.of(leftValue, rightValue)));

                          }

                        } else {

                          c.output(KV.of(e.getKey(), KV.of(leftValue, nullValue)));

                        }

                      }

                    }

                  }))

          .setCoder(

              KvCoder.of(

                  ((KvCoder) leftCollection.getCoder()).getKeyCoder(),

                  KvCoder.of(

                      ((KvCoder) leftCollection.getCoder()).getValueCoder(),

                      ((KvCoder) rightCollection.getCoder()).getValueCoder())));

    }

  }



  /**

   * PTransform representing a right outer join of two collections of KV elements.

   *

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   */

  public static class RightOuterJoin<K, V1, V2>

      extends PTransform<PCollection<KV<K, V1>>, PCollection<KV<K, KV<V1, V2>>>> {



    private transient PCollection<KV<K, V2>> rightCollection;

    private V1 nullValue;



    private RightOuterJoin(PCollection<KV<K, V2>> rightCollection, V1 nullValue) {

      this.rightCollection = rightCollection;

      this.nullValue = nullValue;

    }



    public static <K, V1, V2> RightOuterJoin<K, V1, V2> with(

        PCollection<KV<K, V2>> rightCollection, V1 nullValue) {

      return new RightOuterJoin<>(rightCollection, nullValue);

    }



    @Override

    public PCollection<KV<K, KV<V1, V2>>> expand(PCollection<KV<K, V1>> leftCollection) {

      checkNotNull(leftCollection);

      checkNotNull(rightCollection);

      checkNotNull(nullValue);



      final TupleTag<V1> v1Tuple = new TupleTag<>();

      final TupleTag<V2> v2Tuple = new TupleTag<>();



      PCollection<KV<K, CoGbkResult>> coGbkResultCollection =

          KeyedPCollectionTuple.of(v1Tuple, leftCollection)

              .and(v2Tuple, rightCollection)

              .apply("CoGBK", CoGroupByKey.create());



      return coGbkResultCollection

          .apply(

              "Join",

              ParDo.of(

                  new DoFn<KV<K, CoGbkResult>, KV<K, KV<V1, V2>>>() {

                    @ProcessElement

                    public void processElement(ProcessContext c) {

                      KV<K, CoGbkResult> e = c.element();



                      Iterable<V1> leftValuesIterable = e.getValue().getAll(v1Tuple);

                      Iterable<V2> rightValuesIterable = e.getValue().getAll(v2Tuple);



                      for (V2 rightValue : rightValuesIterable) {

                        if (leftValuesIterable.iterator().hasNext()) {

                          for (V1 leftValue : leftValuesIterable) {

                            c.output(KV.of(e.getKey(), KV.of(leftValue, rightValue)));

                          }

                        } else {

                          c.output(KV.of(e.getKey(), KV.of(nullValue, rightValue)));

                        }

                      }

                    }

                  }))

          .setCoder(

              KvCoder.of(

                  ((KvCoder) leftCollection.getCoder()).getKeyCoder(),

                  KvCoder.of(

                      ((KvCoder) leftCollection.getCoder()).getValueCoder(),

                      ((KvCoder) rightCollection.getCoder()).getValueCoder())));

    }

  }



  /**

   * PTransform representing a full outer join of two collections of KV elements.

   *

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   */

  public static class FullOuterJoin<K, V1, V2>

      extends PTransform<PCollection<KV<K, V1>>, PCollection<KV<K, KV<V1, V2>>>> {



    private transient PCollection<KV<K, V2>> rightCollection;

    private V1 leftNullValue;

    private V2 rightNullValue;



    private FullOuterJoin(

        PCollection<KV<K, V2>> rightCollection, V1 leftNullValue, V2 rightNullValue) {

      this.rightCollection = rightCollection;

      this.leftNullValue = leftNullValue;

      this.rightNullValue = rightNullValue;

    }



    public static <K, V1, V2> FullOuterJoin<K, V1, V2> with(

        PCollection<KV<K, V2>> rightCollection, V1 leftNullValue, V2 rightNullValue) {

      return new FullOuterJoin<>(rightCollection, leftNullValue, rightNullValue);

    }



    @Override

    public PCollection<KV<K, KV<V1, V2>>> expand(PCollection<KV<K, V1>> leftCollection) {

      checkNotNull(leftCollection);

      checkNotNull(rightCollection);

      checkNotNull(leftNullValue);

      checkNotNull(rightNullValue);



      final TupleTag<V1> v1Tuple = new TupleTag<>();

      final TupleTag<V2> v2Tuple = new TupleTag<>();



      PCollection<KV<K, CoGbkResult>> coGbkResultCollection =

          KeyedPCollectionTuple.of(v1Tuple, leftCollection)

              .and(v2Tuple, rightCollection)

              .apply("CoGBK", CoGroupByKey.create());



      return coGbkResultCollection

          .apply(

              "Join",

              ParDo.of(

                  new DoFn<KV<K, CoGbkResult>, KV<K, KV<V1, V2>>>() {

                    @ProcessElement

                    public void processElement(ProcessContext c) {

                      KV<K, CoGbkResult> e = c.element();



                      Iterable<V1> leftValuesIterable = e.getValue().getAll(v1Tuple);

                      Iterable<V2> rightValuesIterable = e.getValue().getAll(v2Tuple);

                      if (leftValuesIterable.iterator().hasNext()

                          && rightValuesIterable.iterator().hasNext()) {

                        for (V2 rightValue : rightValuesIterable) {

                          for (V1 leftValue : leftValuesIterable) {

                            c.output(KV.of(e.getKey(), KV.of(leftValue, rightValue)));

                          }

                        }

                      } else if (leftValuesIterable.iterator().hasNext()

                          && !rightValuesIterable.iterator().hasNext()) {

                        for (V1 leftValue : leftValuesIterable) {

                          c.output(KV.of(e.getKey(), KV.of(leftValue, rightNullValue)));

                        }

                      } else if (!leftValuesIterable.iterator().hasNext()

                          && rightValuesIterable.iterator().hasNext()) {

                        for (V2 rightValue : rightValuesIterable) {

                          c.output(KV.of(e.getKey(), KV.of(leftNullValue, rightValue)));

                        }

                      }

                    }

                  }))

          .setCoder(

              KvCoder.of(

                  ((KvCoder) leftCollection.getCoder()).getKeyCoder(),

                  KvCoder.of(

                      ((KvCoder) leftCollection.getCoder()).getValueCoder(),

                      ((KvCoder) rightCollection.getCoder()).getValueCoder())));

    }

  }



  /**

   * Inner join of two collections of KV elements.

   *

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> innerJoin(

      final PCollection<KV<K, V1>> leftCollection, final PCollection<KV<K, V2>> rightCollection) {

    return innerJoin("InnerJoin", leftCollection, rightCollection);

  }



  /**

   * Inner join of two collections of KV elements.

   *

   * @param name Name of the PTransform.

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> innerJoin(

      final String name,

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection) {

    return leftCollection.apply(name, InnerJoin.with(rightCollection));

  }



  /**

   * Left Outer Join of two collections of KV elements.

   *

   * @param name Name of the PTransform.

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param nullValue Value to use as null value when right side do not match left side.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2. Values that should be null or empty is replaced with nullValue.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> leftOuterJoin(

      final String name,

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection,

      final V2 nullValue) {

    return leftCollection.apply(name, LeftOuterJoin.with(rightCollection, nullValue));

  }



  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> leftOuterJoin(

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection,

      final V2 nullValue) {

    return leftOuterJoin("LeftOuterJoin", leftCollection, rightCollection, nullValue);

  }



  /**

   * Right Outer Join of two collections of KV elements.

   *

   * @param name Name of the PTransform.

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param nullValue Value to use as null value when left side do not match right side.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2. Values that should be null or empty is replaced with nullValue.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> rightOuterJoin(

      final String name,

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection,

      final V1 nullValue) {

    return leftCollection.apply(name, RightOuterJoin.with(rightCollection, nullValue));

  }



  /**

   * Right Outer Join of two collections of KV elements.

   *

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param nullValue Value to use as null value when left side do not match right side.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2. Values that should be null or empty is replaced with nullValue.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> rightOuterJoin(

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection,

      final V1 nullValue) {

    return rightOuterJoin("RightOuterJoin", leftCollection, rightCollection, nullValue);

  }



  /**

   * Full Outer Join of two collections of KV elements.

   *

   * @param name Name of the PTransform.

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param leftNullValue Value to use as null value when left side do not match right side.

   * @param rightNullValue Value to use as null value when right side do not match right side.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2. Values that should be null or empty is replaced with

   *     leftNullValue/rightNullValue.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> fullOuterJoin(

      final String name,

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection,

      final V1 leftNullValue,

      final V2 rightNullValue) {

    return leftCollection.apply(

        name, FullOuterJoin.with(rightCollection, leftNullValue, rightNullValue));

  }



  /**

   * Full Outer Join of two collections of KV elements.

   *

   * @param leftCollection Left side collection to join.

   * @param rightCollection Right side collection to join.

   * @param leftNullValue Value to use as null value when left side do not match right side.

   * @param rightNullValue Value to use as null value when right side do not match right side.

   * @param <K> Type of the key for both collections

   * @param <V1> Type of the values for the left collection.

   * @param <V2> Type of the values for the right collection.

   * @return A joined collection of KV where Key is the key and value is a KV where Key is of type

   *     V1 and Value is type V2. Values that should be null or empty is replaced with

   *     leftNullValue/rightNullValue.

   */

  public static <K, V1, V2> PCollection<KV<K, KV<V1, V2>>> fullOuterJoin(

      final PCollection<KV<K, V1>> leftCollection,

      final PCollection<KV<K, V2>> rightCollection,

      final V1 leftNullValue,

      final V2 rightNullValue) {

    return fullOuterJoin(

        "FullOuterJoin", leftCollection, rightCollection, leftNullValue, rightNullValue);

  }

}